Semiconductor devices including active fins and methods of manufacturing the same

ABSTRACT

Semiconductor devices may include a plurality of active fins each extending in a first direction on a substrate, a gate structure extending on the active fins in a second direction, and a first source/drain layer on first active fins of the active fins adjacent the gate structure. At least one of two opposing sidewalls of a cross-section of the first source/drain layer taken along the second direction may include a curved portion having a slope with respect to an upper surface of the substrate. The slope may decrease from a bottom toward a top thereof.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to Korean PatentApplication No. 10-2015-0044046, filed on Mar. 30, 2015, in the KoreanIntellectual Property Office (KIPO), the disclosure of which is hereinincorporated by reference in its entirety.

BACKGROUND

Example embodiments relate to semiconductor devices and methods ofmanufacturing the same. More particularly, example embodiments relate tofin-type field effect transistors (finFETs) and methods of manufacturingthe same.

When finFas are formed, dummy gate structures may be formed on activefins, recesses may be formed at upper portions of the active fins thatare not covered by the dummy gate structures, and a selective epitaxialgrowth (SEG) process may be performed to form source/drain layersfilling the recesses. When the active fins are close each other, thesource/drain layers on neighboring active fins may contact each other soas not to be electrically isolated.

SUMMARY

Example embodiments may provide a semiconductor device having a goodreliability.

Example embodiments may provide a method of manufacturing asemiconductor device having a good reliability.

A semiconductor device may include a plurality of active fins eachextending in a first direction on a substrate, a gate structure on theplurality of active fins, and a first source/drain layer on theplurality of active fins and adjacent a side of the gate structure. Thegate structure may extend in a second direction that is different fromthe first direction. At least one of opposing sidewalls of across-section of the first source/drain layer that is taken along thesecond direction may include a first curved portion having a slope withrespect to an upper surface of the substrate, and an absolute value ofthe slope of the first curved portion may decrease from a bottom of thefirst curved portion that is close to the substrate to a top thereof.

In various embodiments, the cross-section of the first source/drainlayer may include an upper surface including first and second linearportions having first and second slopes, respectively, with respect tothe upper surface of the substrate, a lower surface including third andfourth linear portions having the first and second slopes, respectively,with respect to the upper surface of the substrate; the sidewalls eachconnecting the upper surface and the lower surface.

According to various embodiments, the lower surface of the cross-sectionof the first source/drain layer may further include a fifth linearportion connecting one of the third linear portions to one of the fourthlinear portions and having a zero degree slope with respect to the uppersurface of the substrate.

In various embodiments, the plurality of active fins may include twofirst active fins. The cross-section of the first source/drain layer mayinclude an upper surface including two first linear portions each havinga first slope with respect to the upper surface of the substrate and twosecond linear portions each having a second slope with respect to theupper surface of the substrate and a lower surface including two thirdlinear portions each having the first slope with respect to the uppersurface of the substrate, two fourth linear portions each having thesecond slope with respect to the upper surface of the substrate, and twofifth linear portions each connecting one of the third linear portionsto one of the fourth linear portions. A first sidewall of the sidewallsof the cross-section of the first source/drain layer may connect one ofthe first linear portions of the upper surface and one of the fourthlinear portions of the lower surface, and a second sidewall of thesidewalls may connect one of the second linear portions of the uppersurface and one of the third linear portions of the lower surface.

In various embodiments, the opposing sidewalls of the cross-section ofthe first source/drain layer may be symmetrical with respect to animaginary line passing a center of the first source/drain layer andextending in a vertical direction that is substantially perpendicular tothe upper surface of the substrate.

According to various embodiments, the plurality of active fins mayinclude a plurality of first active fins in a first region of thesubstrate and a plurality of second active fins in a second region ofthe substrate, and the second region may be spaced apart from the firstregion in the second direction. The semiconductor device may furtherinclude a second source/drain layer. At least one of opposing sidewallsof a cross-section of the second source/drain layer that is taken alongthe second direction may include a second curved portion having a slopewith respect to the upper surface of the substrate, and an absolutevalue of the slope of the second curved portion may decrease from abottom of the second curved portion that is close to the substrate to atop thereof. The first and second source/drain layers may be spacedapart from each other in the second direction.

In various embodiments, a distance between ones of the plurality offirst active fins and a distance between ones of the plurality of secondactive fins may be less than a distance between the plurality of firstactive fins and the plurality of second active fins.

According to various embodiments, the first source/drain layer mayinclude silicon-germanium, silicon and/or silicon carbide.

According to various embodiments, the gate structure may include aninterface pattern, a gate insulation pattern and a gate electrodesequentially stacked on the plurality of active fins.

In various embodiments, the interface pattern, the gate insulationpattern and the gate electrode may include silicon oxide, a metal oxidehaving a dielectric constant higher than silicon oxide, and a metal,respectively.

According to various embodiments, the semiconductor device may furtherinclude gate spacers on respective opposing sidewalls of the gatestructure that are spaced apart from each other in the first direction.The first source/drain layer may contact an outer sidewall of one of thegate spacers.

A semiconductor device may include an active fin on a substrate, a gatestructure on the active fin and a source/drain layer on the active finand adjacent a side of the gate structure. At least one of opposingsidewalls of a cross-section of the source/drain layer may include acurved portion having a slope with respect to an upper surface of thesubstrate, and an absolute value of the slope of the curved portion maydecrease from a bottom of the curved portion that is close to thesubstrate to a top thereof.

In various embodiments, the substrate may include first and secondregions. The active fin may include a plurality of first active fins inthe first region and a plurality of second active fins in the secondregion, and the source/drain layer may include a first source/drainlayer on the plurality of first active fins and a second source/drainlayer on the plurality of second active fins.

According to various embodiments, each of the plurality of first activefins and the plurality of second active fins may extend in a firstdirection, and the plurality of first active fins and the plurality ofsecond active fins may be arranged in a second direction that isdifferent from the first direction. The first and second regions may bespaced apart from each other in the second direction, and thecross-section of the source/drain layer may be taken along the seconddirection.

According to various embodiments, a distance between ones of theplurality of first active fins and a distance between ones of theplurality of second active fins may be less than a distance between theplurality of first active fins and the plurality of second active fins,and the first and second source/drain layers may be spaced apart fromeach other in the second direction.

A semiconductor device may include a plurality of active fins eachextending in a first direction on a substrate, a gate structure on theplurality of active fins, gate spacers on respective sidewalls of thegate structure opposed to each other in the first direction and a firstsource/drain layer on the plurality of active fins and adjacent thesidewall of the gate structure. The gate structure may extend in asecond direction that is different from the first direction. An uppersurface of the first source/drain layer may be higher than lowersurfaces of the gate spacers, and the first source/drain layer may bespaced apart from one of the gate spacers in the first direction.

In various embodiments, the semiconductor device may further include acontact plug electrically connected to the first source/drain layer, andthe contact plug may be disposed in a space between the one of the gatespacers and the first source/drain layer.

In various embodiments, at least one of opposing sidewalls of across-section of the first source/drain layer that is taken along thesecond direction may include a first curved portion having a slope withrespect to an upper surface of the substrate, and an absolute value ofthe slope of the first curved portion may decrease from a bottom of thefirst curved portion that is close to the substrate to a top thereof.

According to various embodiments, the plurality of active fins mayinclude a plurality of first active fins in a first region of thesubstrate and a plurality of second active fins in a second region ofthe substrate, the first and second regions may be spaced apart fromeach other in the second direction, and the first source/drain layer maybe on the plurality of first active fins. The semiconductor device mayfurther include a second source/drain layer on the second active fins,at least one of opposing sidewalls of a cross-section of the secondsource/drain layer that is taken along the second direction may includea second curved portion having a slope with respect to the upper surfaceof the substrate, and an absolute value of the slope of the secondcurved portion may decrease from a bottom of the second curved portionthat is close to the substrate to a top thereof. The first and secondsource/drain layers may be spaced apart from each other in the seconddirection.

In various embodiments, the first source/drain layer may include anepitaxial layer including silicon and/or silicon carbide, and the secondsource/drain layer may include an epitaxial layer includingsilicon-germanium.

A method of manufacturing a semiconductor device may include forming aplurality of first active fins and a plurality of second active fins ona substrate. Ones of the plurality of first active fins may extend in afirst direction and may be spaced apart from each other in a seconddirection that is different from the first direction by a firstdistance. Ones of the plurality of second active fins may extend in thefirst direction and may be spaced apart from each other in the seconddirection by a second distance. The plurality of first active fins maybe spaced apart from the plurality of second active fins in the seconddirection by a third distance that may be greater than the first andsecond distances. The method may also include forming first fin spacerson respective sidewalls of the plurality of first active fins and secondfin spacers on respective sidewalls of the plurality of second activefins and forming a sacrificial layer on the plurality of first activefins, the plurality of second active fins and the first and second finspacers. Portions of the sacrificial layer formed between the first finspacers and between the second fin spacers each may include an air gaptherein. The method may further include removing an upper portion of thesacrificial layer to expose upper surfaces of the plurality of firstactive fins and the plurality of second active fins, partially removingthe plurality of first active fins and the plurality of second activefins to form first and second recesses, respectively, removing the firstand second fin spacers and the portions of the sacrificial layer formedbetween the first fin spacers and between the second fin spacers andperforming a selective epitaxial growth (SEG) process using theplurality of first active fins and the plurality of second active finsexposed in the first and second recesses to form first and secondsource/drain layers, respectively.

In various embodiments, forming the sacrificial layer on the substratemay include forming the sacrificial layer having a low step coverage,and the sacrificial layer may be formed in a space between the pluralityof first active fins and the plurality of second active fins.

According to various embodiments, removing the first and second finspacers and the portions of the sacrificial layer formed between thefirst fin spacers and between the second fin spacers may includepartially removing the sacrificial layer formed in the space between theplurality of first active fins and the plurality of second active finssuch that the sacrificial layer may remain in the space.

According to various embodiments, the method may additionally include,prior to forming the first and second fin spacers, forming a dummy gatestructure crossing over the plurality of first active fins and theplurality of the second active fins. Forming the first and second finspacers may further include forming a gate spacer on a sidewall of thedummy gate structure.

In various embodiments, removing the upper portion of the sacrificiallayer to expose the upper surfaces of the plurality of first active finsand the plurality of second active fins may include performing aChemical Mechanical Planarization (CMP) process on the sacrificial layeruntil an upper surface of the dummy gate structure is exposed andperforming an etch back process on the sacrificial layer until the uppersurfaces of the plurality of first active fins and the plurality ofsecond active fins are exposed.

In various embodiments, partially removing the plurality of first activefins and the plurality of second active fins to form the first andsecond recesses may include partially etching the plurality of firstactive fins and the plurality of second active fins exposed by thesacrificial layer using the dummy gate structure and the gate spacer asan etching mask.

According to various embodiments, the dummy gate structure may include adummy gate insulation pattern and a dummy gate electrode sequentiallystacked on the substrate, and the method further include, afterperforming the SEG process to form the first and second source/drainlayers, removing the sacrificial layer, forming an insulating interlayeron the dummy gate structure, the gate spacer, and the first and secondsource/drain layer, planarizing the insulating interlayer until thedummy gate electrode of the dummy gate structure is exposed, removingthe dummy gate electrode and the dummy gate insulation pattern to forman opening exposing upper surfaces of the plurality of first and secondactive fins and forming a gate structure in the opening.

A method of manufacturing a semiconductor device may include forming aplurality of first active fins and a plurality of second active fins ona substrate. Ones of the plurality of first active fins and ones of theplurality of second active fins may be arranged in a direction. Themethod may also include forming a sacrificial layer on the substrate.The sacrificial layer may include a first recess exposing the pluralityof first active fins and a second recess exposing the plurality ofsecond active fins. The method may further includeperforming anepitaxial growth process using the plurality of first active fins andthe plurality of second active fins exposed in the first and secondrecesses as seed layers to form a first source/drain layer contactingthe plurality of first active fins in the first recess and a secondsource/drain layer contacting the plurality of second active fins in thesecond recess.

In various embodiments, the method may additionally include forming aplurality of first preliminary active fins and a plurality of secondpreliminary active fins on the substrate, forming first spacers onrespective sidewalls of the plurality of first preliminary active finsand second spacers on respective sidewalls of the plurality of secondpreliminary active fins and forming the sacrificial layer on thesubstrate between ones of the plurality of first preliminary activefins, between ones of the plurality of second preliminary active finsand between the plurality of first preliminary active fins and theplurality of second preliminary active fins. The sacrificial layer mayexpose upper surfaces of the plurality of first preliminary active finsand the plurality of second preliminary active fins. The method mayfurther include removing upper portions of the plurality of firstpreliminary active fins and the plurality of second preliminary activefins to form the plurality of first active fins and the plurality ofsecond active fins, respectively and removing the first and second finspacers and portions of the sacrificial layer formed between the ones ofthe plurality of first active fins and between the ones of the pluralityof second active fins to form the first and second recesses in thesacrificial layer.

According to various embodiments, the first source/drain layer mayinclude a curved sidewall protruding outwardly when viewed in crosssection.

According to various embodiments, the curved sidewall of the firstsource/drain layer may have a slope with respect to an upper surface ofthe substrate, and an absolute value of the slope may decrease from abottom of the curved sidewall that is close to the substrate to a topthereof.

In various embodiments, the sacrificial layer formed between the ones ofthe plurality of first preliminary active fins and between the ones ofthe plurality of second preliminary active fins may include cavitiestherein. Removing the portions of the sacrificial layer may includeentirely removing the portions of the sacrificial layer formed betweenthe ones of the plurality of first active fins and between the ones ofthe plurality of second active fins and partially removing a portion ofthe sacrificial layer formed between the plurality of first active finsand the plurality of second active fins by performing a wet etchingprocess.

In various embodiments, the ones of the plurality of first active finsmay be arranged in the direction by a first distance, the ones of theplurality of second active fins may be arranged in the direction by asecond distance, and the plurality of first active fins are spaced apartfrom the plurality of second active fins in the direction by a thirddistance that is greater than the first distance and the seconddistance.

According to various embodiments, opposing sides of the firstsource/drain layer and opposing sides of the second source/drain layermay contact the sacrificial layer after performing the epitaxial growthprocess.

According to various embodiments, the method may include removing thesacrificial layer after performing the epitaxial growth process andperforming an additional epitaxial growth process using the firstsource/drain layer and the second source/drain layer as a seed layer.

A method of manufacturing a semiconductor device may include forming aplurality of first active fins on a substrate, forming a gate structurecrossing over the plurality of first active fins and forming a firstsource/drain layer on the plurality of first active fins and adjacent aside of the gate structure. A sidewall of the first source/drain layermay include a first curved portion when viewed in cross section, thefirst curved portion may have a slope with respect to an upper surfaceof the substrate, and an absolute value of the slope of the first curvedportion may decrease from a bottom of the first curved portion that isclose to the substrate to a top thereof.

According to various embodiments, the first source/drain layer mayinclude an upper surface including first linear portions having a firstslope with respect to the upper surface of the substrate and secondlinear portions including a second slope with respect to the uppersurface of the substrate. A lower surface including third linearportions having the first slope with respect to the upper surface of thesubstrate and fourth linear portions including the second slope withrespect to the upper surface of the substrate. The sidewall may connectthe upper surface and the lower surface.

In various embodiments, the method may also include forming a pluralityof second active fins on the substrate and forming a second source/drainlayer on the plurality of second active fins and adjacent the side ofthe gate structure. A sidewall of the second source/drain layer mayinclude a second curved portion when viewed in cross section, the secondcurved portion may have a slope with respect to the upper surface of thesubstrate, and an absolute value of the slope of the second curvedportion may decrease from a bottom of the second curved portion that isclose to the substrate to a top thereof. Ones of the plurality of firstactive fins may be arranged in a direction by a first distance, ones ofthe plurality of second active fins may be arranged in the direction bya second distance, and the plurality of first active fins may be spacedapart from the plurality of second active fins in the direction by athird distance that may be greater than the first distance and thesecond distance.

In various embodiments, the method may further include forming gatespacers on respective opposing sidewalls of the gate structure. An uppersurface of the first source/drain layer may be higher than lowersurfaces of the gate spacers, and ones of the plurality of first activefins may extend in a first direction, and the first source/drain layermay be spaced apart from one of the gate spacers in the first direction.

According to various embodiments, the method may include forming acontact plug electrically connected to the first source/drain layer, andthe contact plug may be disposed between the first source/drain layerand the one of the gate spacers.

According to example embodiments, even if the semiconductor device mayinclude active fins spaced apart from each other by small distances, thefirst and second source/drain layers on the active fins may beelectrically insulated from each other.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings. FIGS. 1 to 63 represent non-limiting, example embodiments asdescribed herein.

FIGS. 1, 2A, 2B, 3 and 4 are plan views and cross-sectional viewsillustrating a semiconductor device in accordance with exampleembodiments;

FIG. 5 is a cross-sectional view illustrating a semiconductor device inaccordance with example embodiments;

FIGS. 6 to 43 are plan views and cross-sectional views illustrating amethod of manufacturing a semiconductor device in accordance withexample embodiments;

FIGS. 44 and 45 are cross-sectional views illustrating a semiconductordevice in accordance with example embodiments;

FIGS. 46 to 51 are plan views and cross-sectional views illustrating amethod of manufacturing a semiconductor device in accordance withexample embodiments;

FIGS. 52 and 54 are a plan view and cross-sectional views illustrating asemiconductor device in accordance with example embodiments; and

FIGS. 55 to 63 are plan views and cross-sectional views illustrating amethod of manufacturing a semiconductor device in accordance withexample embodiments.

DESCRIPTION OF EMBODIMENTS

Various example embodiments will be described more fully hereinafterwith reference to the accompanying drawings, in which some exampleembodiments are shown. The present inventive concepts may, however, beembodied in many different forms and should not be construed as limitedto the example embodiments set forth herein. Rather, these exampleembodiments are provided so that this description will be thorough andcomplete and will fully convey the scope of the present inventiveconcepts to those skilled in the art. In the drawings, the sizes andrelative sizes of layers and regions may be exaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third,fourth etc. may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the present inventive concepts.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting of thepresent inventive concepts. As used herein, the singular forms “a,” “an”and “the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Example embodiments are described herein with reference tocross-sectional or plan view illustrations that are schematicillustrations of idealized example embodiments (and intermediatestructures). As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, example embodiments should not be construed aslimited to the particular shapes of regions illustrated herein but areto include deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofthe present inventive concepts.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this inventive concepts belongs.It will be further understood that terms, such as those defined incommonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand will not be interpreted in an idealized or overly formal senseunless expressly so defined herein.

FIGS. 1, 2A, 2B, 3 and 4 are plan views and cross-sectional viewsillustrating a semiconductor device in accordance with exampleembodiments. FIG. 1 is a plan view illustrating the semiconductordevice, and FIGS. 2A, 2B, 3 and 4 are cross-sectional views illustratingthe semiconductor device.

FIG. 2A is a cross-sectional view taken along the line A-A′ of FIG. 1,FIG. 2B is an enlarged view of the region A in FIG. 2A, FIG. 3 is across-sectional view taken along the line B-B′ of FIG. 1, and FIG. 4 isa cross-sectional view taken along the line C-C′ of FIG. 1.

Referring to FIGS. 1, 2A, 2B, 3 and 4, the semiconductor device mayinclude an active fin 105, a gate structure 290, and source/drain layers232 and 234 on a substrate 100. The semiconductor device may furtherinclude a gate spacer 160, contact plugs 330 and 335, metal silicidepatterns 320 and 325, and insulating interlayers 240 and 300.

The substrate 100 may include a semiconductor material, e.g., silicon,germanium, silicon-germanium, etc., or III-V semiconductor compounds,e.g., GaP, GaAs, GaSb, etc. In some embodiments, the substrate 100 maybe a silicon-on-insulator (SOI) substrate, or a germanium-on-insulator(GOI) substrate.

The substrate 100 may include a first region I and a second region II.The first and second regions I and II may be adjacent to each other in asecond direction that is substantially parallel to an upper surface ofthe substrate 100. In some embodiments, the first and second regions Iand II may be a negative-channel metal oxide semiconductor (NMOS) regionand a positive-channel metal oxide semiconductor (PMOS) region,respectively, or a PMOS region and an NMOS region, respectively.Alternatively, both of the first and second regions I and II may bewithin an NMOS region or within a PMOS region. Hereinafter, only thecase in which the first and second regions I and II are NMOS and PMOSregions, respectively, will be illustrated.

Isolation patterns 120 and 125 may be formed on the substrate 100, andthus a field region and an active region may be defined in the substrate100. An upper surface of the field region may be covered by theisolation patterns 120 and 125, and an upper surface of the activeregion may not be covered by the isolation patterns 120 and 125. Theactive region may have a fin-like shape protruding upwardly, and thusmay be referred to as an active fin 105.

In some embodiments, one of the isolation patterns 120 and 125, whichmay be formed within one of the first and second regions I and II, maybe referred to as a first isolation pattern 120, and one of theisolation patterns 120 and 125, which may be formed at an interfacebetween the first and second regions I and II to extend over both of thefirst and second regions I and II, may be referred to as a secondisolation pattern 125. In some embodiments, the second isolation pattern125 may have a width in the second direction greater than that of thefirst isolation pattern 120.

In some embodiments, the active fin 105 may extend in a first directionthat is substantially parallel to the upper surface of the substrate 100and substantially perpendicular to the second direction, and a pluralityof active fins 105 may be formed and be arranged in the seconddirection. The active fins 105 in the first and second regions I and II,respectively, may be referred to as first and second active fins,respectively. In some embodiments, the first active fins may be spacedapart from each other in the second direction by a first distance, thesecond active fins may be spaced apart from each other in the seconddirection by a second distance, and the first and second active finsadjacent to each other at the interface between the first and secondregions I and II may be spaced apart from each other in the seconddirection by a third distance. The first and second distances may besubstantially the same and may be less than the third distance.

In some embodiments, the active fin 105 may include lower and upperactive patterns 105 b and 105 a sequentially stacked and integrallyformed with each other. In some embodiments, the active fin 105 may havea unitary structure including lower and upper active patterns 105 b and105 a. A sidewall of the lower active pattern 105 b may be covered bythe isolation patterns 120 and 125, and the upper active pattern 105 amay protrude from upper surfaces of the isolation patterns 120 and 125.In some embodiments, the lower active pattern 105 b may have a width inthe second direction slightly greater than that of the upper activepattern 105 a.

The gate structure 290 may extend in the second direction, and may beformed on the active fin 105 and the isolation patterns 120 and 125. Insome embodiments, a plurality of gate structures 290 may be formed inthe first direction and may be spaced apart from each other in the firstdirection.

The gate structure 290 may include an interface pattern 260, a gateinsulation pattern 270 and a gate electrode 280 sequentially stacked.

In some embodiments, the interface pattern 260 may be formed only on anupper surface of the active fin 105, and the gate insulation pattern 270may be formed on the interface pattern 260, the isolation patterns 120and 125, and an inner sidewall of the gate spacer 160. Alternatively,the interface pattern 260 may be formed not only on the active fin 105,but also on the isolation patterns 120 and 125, and the inner sidewallof the gate spacer 160. In some embodiments, the interface pattern 260may not be formed, and thus the gate structure 290 may include nointerface pattern therein. A bottom and a sidewall of the gate electrode280 may be covered by the gate insulation pattern 270.

The interface pattern 260 may include an oxide, e.g., silicon oxide, thegate insulation pattern 270 may include a metal oxide having adielectric constant higher than silicon oxide, e.g., hafnium oxide,tantalum oxide, zirconium oxide, etc., and the gate electrode 280 mayinclude a metal having a low electrical resistance, e.g., aluminum,copper, tantalum, etc., or a metal nitride.

The gate spacer 160 may be formed on sidewalls of the gate structure 290opposed to each other in the first direction. The gate spacer mayinclude a nitride, e.g., silicon nitride.

One of the source/drain layers 232 and 234 in the first region I may bereferred to as a first source/drain layer 232, and one of thesource/drain layers 232 and 234 in the second region II may be referredto as a second source/drain layer 234.

Each of the source/drain layers 232 and 234 may be formed on at leastone of the active fins 105 disposed in the second direction adjacent thegate structure 290 extending in the second direction. Referring to FIG.4, each of the source/drain layers 232 and 234 may fill a recess (notshown) that may be formed at the upper active pattern 105 a to exposethe lower active pattern 105 b, and an upper portion of each of thesource/drain layers 232 and 234 may contact an outer sidewall of thegate spacer 160. Referring to FIG. 2A, each of the source/drain layers232 and 234 may contact upper surfaces of the lower active patterns 105b, and may protrude upwardly.

FIGS. 1 to 4 show that the first source/drain layer 232 is formed on twoactive fins and the second source/drain layer 234 is formed on threeactive fins, however, the inventive concepts may not be limited thereto.That is, each of the source/drain layers 232 and 234 may be formed on aplurality of active fins 105 adjacent to each other in each of the firstand second regions I and II, and further may be formed on only oneactive fin 105.

At least one of two sidewalls of a cross-section of each of thesource/drain layers 232 and 234 taken along the second direction mayinclude a curved portion having a slope decreasing (e.g., graduallydecreasing) from a bottom toward a top thereof. In some embodiments,steepness (i.e., an absolute value of a slope) of the curved portion ofthe cross-section of each of the source/drain layers 232 and 234 maydecrease from a bottom of the curved portion that is close to thesubstrate 100 toward a top thereof.

Hereinafter, the shape of the cross-section of the first source/drainlayer 232 on two active fins taken along the second direction will beillustrated with reference to FIG. 2B.

The cross-section of the first source/drain layer 232 taken along thesecond direction may include an upper surface, a lower surface and asidewall. The sidewall of the cross-section of the first source/drainlayer 232 may protrude outwardly.

The upper surface of the cross-section may include two first linearportions 11 a and 11 b each having a first slope with respect to theupper surface of the substrate 100, and two second linear portions 12 aand 12 b each having a second slope with respect to the upper surface ofthe substrate 100. Thus, the upper surface of the cross-section may beformed by the first linear portion 11 a, the second linear portion 12 a,the first linear portion 11 b, and the second linear portion 12 bconnected with each other in this order. When the first slope is apositive slope with respect to the upper surface of the substrate 100,the second slope may be a negative slope with respect to the uppersurface of the substrate 100.

The lower surface of the cross-section may include two third linearportions 13 a and 13 b each having the first slope with respect to theupper surface of the substrate 100, two fourth linear portions 14 a and14 b each having the second slope with respect to the upper surface ofthe substrate 100, and two fifth linear portions 15 a and 15 b having azero degree slope with respect to the upper surface of the substrate100. Thus, the lower surface of the cross-section may be formed by thefourth linear portion 14 a, the fifth linear portion 15 a, the thirdlinear portion 13 a, the fourth linear portion 14 b, the fifth linearportion 15 b, and the third linear portion 13 b connected with eachother in this order.

A first sidewall of the cross-section may include a first curved portion20 a connecting the first linear portion 11 a of the upper surface andthe fourth linear portion 14 a of the lower surface, and a secondsidewall of the cross-section may include a second curved portion 20 bconnecting the second linear portion 12 b of the upper surface and thethird linear portion 13 b of the lower surface. Each of the first andsecond curved portions 20 a and 20 b may have a slope with respect tothe upper surface of the substrate 100, and an absolute value of theslope may decrease (e.g., gradually decreasing) from a bottom of each ofthe first and second curved portions 20 a and 20 b that is close to thesubstrate 100 toward a top thereof. In some embodiments, the first andsecond sidewalls may be symmetrical with respect to an imaginary linepassing a center of the first source/drain layer 232 and extending in avertical direction that is substantially perpendicular to the uppersurface of the substrate 100.

Each of the first and second source/drain layers 232 and 234 may be anepitaxial layer including a semiconductor material, e.g., silicon,germanium, silicon-germanium, etc. When the first and second regions Iand II are NMOS and PMOS regions, respectively, the first source/drainlayer 232 may include single crystalline silicon or single crystallinesilicon carbide, and the second source/drain layer 234 may includesingle crystalline silicon-germanium. The first and second source/drainlayers 232 and 234 may include n-type impurities, e.g., phosphorus,arsenic, etc., and p-type impurities, e.g., boron, aluminum, etc.,respectively.

In some embodiments, the first and second metal silicide patterns 320and 325 may be formed at upper portions of the first and secondsource/drain layers 232 and 234, respectively. In this case, each of thefirst and second source/drain layers 232 and 234 may be divided into anupper portion including metal and a lower portion including no metaltherein. FIGS. 2A and 2B show that an interface between the upper andlower portions of each of the first and second source/drain layers 232and 234 is curved in the cross-section thereof taken along the seconddirection, however, the inventive concepts may not be limited thereto.In some embodiments, the interface between the upper and lower portionsof each of the first and second source/drain layers 232 and 234 may be aline that may correspond to the upper surface of each of the first andsecond source/drain layers 232 and 234.

In some embodiments, the first and second metal silicide patterns 320and 325 may be separated from the first and second source/drain layers232 and 234, respectively, to be formed on the upper surfaces of thefirst and second source/drain layers 232 and 234, respectively. In someembodiments, the first and second metal silicide patterns 320 and 325may not be formed.

The first insulating interlayer 240 may be formed on the active fin 105and the isolation patterns 120 and 125, and cover the first and secondsource/drain layers 232 and 234 and the first and second metal silicidepatterns 232 and 234. The first insulating interlayer 240 may also coverthe outer sidewalls of the gate spacer 160 on the sidewalls of the gatestructure 290. The second insulating interlayer 300 may be formed on thefirst insulating interlayer 240, and cover the gate structure 290 andthe gate spacer 160. The first and second insulating interlayers 240 and300 may include an oxide, e.g., silicon oxide.

The first and second contact plugs 330 and 335 may penetrate through thefirst and second insulating interlayers 240 and 300, and contact thefirst and second source/drain layers 232 and 234, or the first andsecond metal silicide patterns 320 and 325 thereon. The first and secondcontact plugs 330 and 335 may include, for example, a metal, a metalnitride, doped polysilicon, etc.

In the semiconductor device, the first and second active fins, whichneed to be electrically insulated from each other, among the active fins105, may be formed in the first and second regions I and II,respectively, and thus the first and second source/drain layers 232 and234 on the first and second active fins, respectively, may beelectrically insulated from each other by the first insulatinginterlayer 240. The first source/drain layer 232 may be commonly formedon the first active fins that need not to be electrically insulated fromeach other, or the second source/drain layer 234 may be commonly formedon the second active fins that need not to be electrically insulatedfrom each other. The first active fin may include a single active fin ora plurality of active fins, and the second active fin may include asingle active fin or a plurality of active fins.

Thus, even if the semiconductor device may include the active fins 105spaced apart from each other by a short distance, the first and secondsource/drain layers 232 and 234 on the active fins 105 may beelectrically insulated from each other.

FIG. 5 is a cross-sectional view illustrating a semiconductor device inaccordance with example embodiments. FIG. 5 is a cross-sectional viewtaken along the line A-A′ of FIG. 1. This semiconductor device may besubstantially the same as or similar to that illustrated in FIGS. 1 to4, except for the shape of cross-section of the source/drain layers.Thus, like reference numerals refer to like elements, and detaileddescriptions thereon are omitted herein.

Referring to FIG. 5, the semiconductor device may include the active fin105, the gate structure 290, and third and fourth source/drain layers233 and 235 on the substrate 100. The semiconductor device may furtherinclude the gate spacer 160, the first and second contact plugs 330 and335, the first and second metal silicide patterns 320 and 325, and thefirst and second insulating interlayers 240 and 300.

The shape of the cross-section of the third source/drain layer 233 ontwo first active fins may be as follows.

The cross-section of the third source/drain layer 233 taken along thesecond direction may include an upper surface, a lower surface and asidewall, and the shapes of the upper surface and the lower surfacethereof may be substantially the same as or similar to those of thecross-section of the first source/drain layer 232 illustrated in FIG.2B. Thus, the upper surface of the cross-section may include the twofirst linear portions 11 a and 11 b each having the first slope withrespect to the upper surface of the substrate 100, and the two secondlinear portions 12 a and 12 b each having the second slope with respectto the upper surface of the substrate 100. The lower surface of thecross-section may include the two third linear portions 13 a and 13 beach having the first slope with respect to the upper surface of thesubstrate 100, the two fourth linear portions 14 a and 14 b each havingthe second slope with respect to the upper surface of the substrate 100,and the two fifth linear portions 15 a and 15 b having a zero degreeslope with respect to the upper surface of the substrate 100.

A first sidewall of the cross-section may include a sixth linear portion30 a connecting the first linear portion 11 a of the upper surface andthe fourth linear portion 14 a of the lower surface, and a secondsidewall of the cross-section may include a seventh curved portion 30 bconnecting the second linear portion 12 b of the upper surface and thethird linear portion 13 b of the lower surface. Each of the sixth andseventh linear portions 30 a and 30 b may have a 90 degree slope withrespect to the upper surface of the substrate 100. In some embodiments,the first and second sidewalls may be symmetrical with respect to animaginary line passing a center of the third source/drain layer 233 andextending in a vertical direction that is substantially perpendicular tothe upper surface of the substrate 100.

FIGS. 6 to 43 are plan views and cross-sectional views illustrating amethod of manufacturing a semiconductor device in accordance withexample embodiments. FIGS. 6, 8, 11, 14, 17, 20, 23, 25, 28, 31, 35, 38and 41 are plan views, and FIGS. 7, 9-10, 12-13, 15-16, 18-19, 21-22,24, 26-27, 29-30, 32-34, 36-37, 39-40 and 42-43 are cross-sectionalviews.

FIGS. 7, 12, 16, 18, 21, 24, 26, 29, 32, 34 and 42 are cross-sectionalviews taken along lines A-A′ of corresponding plan views, respectively,FIGS. 9, 36 and 39 are cross-sectional views taken along lines B-B′ ofcorresponding plan views, respectively, and FIGS. 10, 13, 15, 19, 22,27, 30, 33, 37, 40 and 43 are cross-sectional views taken along linesC-C′ of corresponding plan views, respectively.

Referring to FIGS. 6 and 7, an upper portion of a substrate 100 may bepartially removed to form first and second trenches 110 and 115, andfirst and second isolation patterns 120 and 125 may be formed to fillthe first and second trenches 110 and 115, respectively.

The substrate 100 may include a semiconductor material, e.g., silicon,germanium, silicon-germanium, etc., or III-V semiconductor compounds,e.g., GaP, GaAs, GaSb, etc. In some embodiments, the substrate 100 maybe an SOI substrate, or a GOI substrate.

The substrate 100 may include a first region I and a second region II.The first and second regions I and II may be adjacent to each other in asecond direction that is substantially parallel to an upper surface ofthe substrate 100. Hereinafter, the first and second regions I and IIserving as NMOS and PMOS regions, respectively, will be illustrated.

In some embodiments, the first and second isolation patterns 120 and 125may be formed by forming an isolation layer on the substrate 100 tosufficiently fill the first and second trenches 110 and 115, planarizingthe isolation layer until an upper surface of the substrate 100 may beexposed, and removing an upper portion of the isolation layer to exposeupper portions of the first and second trenches 110 and 115. When theupper portions of the isolation layer are removed, a portion of thesubstrate 100 adjacent thereto may be also removed, and thus a width ofa portion of the substrate 100 of which a sidewall may not be covered bythe isolation patterns 120 and 125 may be less than a width of a portionof the substrate 100 of which a sidewall may be covered by the first andsecond isolation patterns 120 and 125. The isolation layer may be formedof an oxide, e.g., silicon oxide.

According as the first and second isolation patterns 120 and 125 areformed on the substrate 100, a field region having an upper surfacecovered by the first and second isolation patterns 120 and 125, and anactive region having an upper surface not covered by the first andsecond isolation patterns 120 and 125 may be defined in the substrate100. The active region may be also referred to as an active fin 105.

In some embodiments, the first trench 110 may be formed within one ofthe first and second regions I and II, and the second trench 115 may beformed at an interface between the first and second regions I and II toextend over both of the first and second regions I and II. In someembodiments, the second trench 115 may have a width in the seconddirection greater than that of the first trench 110.

In some embodiments, the active fin 105 may extend in a first directionthat is substantially parallel to the upper surface of the substrate100, and a plurality of active fins 105 may be formed in the seconddirection. In some embodiment, the first direction may be substantiallyperpendicular to the second direction. The plurality of active fins 105may be spaced apart from each other in the second direction. The activefins 105 in the first and second regions I and II, respectively, may bereferred to as first and second active fins, respectively. In someembodiments, the first active fins may be spaced apart from each otherin the second direction by a first distance, the second active fins maybe spaced apart from each other in the second direction by a seconddistance, and the first and second active fins adjacent to each other atthe interface between the first and second regions I and II may bespaced apart from each other in the second direction by a thirddistance. The first and second distances may be substantially the same,and may be less than the third distance.

In some embodiments, the active fin 105 may include lower and upperactive patterns 105 b and 105 a sequentially stacked and integrallyformed with each other. In some embodiments, the active fin 105 may havea unitary structure including the lower and upper active patterns 105 band 105 a. A sidewall of the lower active pattern 105 b may be coveredby the isolation patterns 120 and 125, and the upper active pattern 105a may protrude from upper surfaces of the isolation patterns 120 and125. In some embodiments, the lower active pattern 105 b may have awidth in the second direction slightly greater than that of the upperactive pattern 105 a.

Referring to FIGS. 8 to 10, a dummy gate structure may be formed on thesubstrate 100.

The dummy gate structure may be formed by sequentially forming a dummygate insulation layer, a dummy gate electrode layer and a gate masklayer on the active fin 105 of the substrate 100 and the isolationpatterns 120 and 125, patterning the gate mask layer by aphotolithography process using a photoresist pattern to form a gate mask150, and sequentially etching the dummy gate electrode layer and thedummy gate insulation layer using the gate mask 150 as an etching mask.Thus, the dummy gate structure may be formed to include a dummy gateinsulation pattern 130, a dummy gate electrode 140 and the gate mask 150sequentially stacked on the substrate 100.

The dummy gate insulation layer may be formed of an oxide, e.g., siliconoxide, the dummy gate electrode layer may be formed of, e.g.,polysilicon, and the gate mask layer may be formed of a nitride, e.g.,silicon nitride. The dummy gate insulation layer may be formed by, forexample, a chemical vapor deposition (CVD) process, an atomic layerdeposition (ALD) process, or the like. In some embodiments, the dummygate insulation layer may be formed by a thermal oxidation process on anupper portion of the substrate 100, and in this case, the dummy gateinsulation layer may be formed only on the active fin 105. The dummygate electrode layer and the gate mask layer may be formed by, forexample, a CVD process, an ALD process, etc.

In some embodiments, the dummy gate structure may be formed to extend inthe second direction on the active fins 105 of the substrate 100 and theisolation patterns 120 and 125, and a plurality of dummy gate structuresmay be formed to be spaced apart from each other in the first direction.

An ion implantation process may be further performed to form an impurityregion (not shown) at an upper portion of the active fin 105 adjacentthe dummy gate structure.

Referring to FIGS. 11 to 13, a gate spacer 160 and a fin spacer 170 maybe formed on sidewalls of the dummy gate structure and the active fin105, respectively.

In some embodiments, the gate spacer 160 and the fin spacer 170 may beformed by forming a spacer layer on the dummy gate structure, the activefin 105, and the isolation patterns 120 and 125, and anisotropicallyetching the spacer layer. The spacer layer may be formed of a nitride,e.g., silicon nitride, silicon oxycarbonitride, etc.

The gate spacer 160 may be formed on the sidewalls of the dummy gatestructure opposed to each other in the first direction, and the finspacer 170 may be formed on the sidewalls of the active fin 105 opposedto each other in the second direction. In some embodiments, a width ofthe gate spacer 160 in the first direction may be greater than a widthof the fin spacer 170 in the second direction.

In some embodiments, an outer sidewall of each of the gate spacer 160and the fin spacer 170 may be a curve having a slope decreasing (e.g.,gradually decreasing) from a bottom toward a top thereof.

Referring to FIGS. 14 to 16, a sacrificial layer 180 may be formed onthe active fin 105 and the isolation patterns 120 and 125 to cover thedummy gate structure, the gate spacer 160 and the fin spacer 170.

In some embodiments, the sacrificial layer 180 may be formed by, forexample, a CVD process under conditions having low step coverage. Thus,an air gap 190 may be formed between ones of the fin spacers 170 onsidewalls of the first active fins or between ones of the fin spacers170 on sidewalls of the second active fins, which may be spaced apartfrom each other by a relatively short distance by the first trench 110,while no air gap may be formed between ones of the fin spacers 170 onsidewalls of the first and second active fins, which may be spaced apartfrom each other by a relatively long distance by the second trench 115.It will be understood that “air gap” may be, for example, any void orcavity, and may be a gap filled with air (e.g., an air-gap), a gapfilled with an inert gas or gases (e.g., an inert gas gap), a gapdefining a vacuum (e.g., a vacuum gap), etc.

The CVD process may be performed under the conditions having low stepcoverage, and thus a thickness of the sacrificial layer 180 on an uppersurface of the dummy gate structure, which may be formed at a relativelyhigh height, may be greater than a thickness of the sacrificial layer180 on an upper surface of the active fin 105, which may be formed at arelatively low height.

Referring to FIGS. 17 to 19, an upper portion of the sacrificial layer180 may be removed until an upper surface of the active fin 105 may beexposed.

In some embodiments, after performing a chemical mechanical polishing(CMP) process on the sacrificial layer 180 until an upper surface of thedummy gate structure may be exposed, an etch back process may beperformed until the upper surface of the active fin 105 may be exposedto remove the upper portion of the sacrificial layer 180.

Thus, first and second sacrificial patterns 182 and 184 may be formedover the first and second trenches 110 and 115, respectively. The airgap 190 may remain in the first sacrificial pattern 182, and no air gapmay exist in the sacrificial pattern 184.

The upper surface of the dummy gate structure and the gate spacer 160 onthe sidewalls thereof may not be covered by the sacrificial patterns 182and 184 but exposed.

Referring to FIGS. 20 to 22, an upper portion of the exposed active fin105 may be removed to form a first recess 200.

In some embodiments, the upper active pattern 105 a of the active fin105 may be removed to form the first recess 200, and thus an uppersurface of the lower active pattern 105 b may be exposed.

Referring to FIGS. 23 to 24, the first sacrificial pattern 182 may beremoved to form a second recess 210, and thus an upper surface of thefirst isolation pattern 120 may be exposed.

In some embodiments, a wet etching process may be performed to removethe first sacrificial pattern 182. During the wet etching process, thesecond sacrificial pattern 184 may be also partially removed, however,the second sacrificial pattern 184 may have a width greater than that ofthe first sacrificial pattern 182 and may have no air gap therein, andthus the second sacrificial pattern 184 may remain even if the firstsacrificial pattern 182 may be completely removed.

Referring to FIGS. 25 to 27, the fin spacer 170 may be removed so thatthe first recess 200 may expand to a third recess 220.

In some embodiments, the fin spacer 170 may be removed by a wet etchingprocess or a dry etching process. During the etching process, the gatespacer 160 may be also partially removed, however, the gate spacer 160may have a thickness greater than that of the fin spacer 170, and thusmay remain even if the fin spacer 170 may be completely removed.

The third recess 220 formed by the etching process may expose the uppersurface of the active fin 105, i.e., of the lower active pattern 105 b,and each of sidewalls of the third recess 220 opposed to each other inthe second direction may have a curved shape with a slope decreasing(e.g., gradually decreasing) from a bottom toward a top thereof whenviewed from the first direction, which may correspond to the shape ofthe outer sidewall of the fin spacer 170.

Referring to FIGS. 28 to 30, first and second source/drain layers 232and 234 partially filling the third recess 220 may be formed on thefirst and second active fins, respectively.

In some embodiments, the first and second source/drain layers 232 and234 may be formed by a selective epitaxial growth (SEG) process usingthe upper surface of the active fin 105 exposed by the third recess 220as a seed layer.

In some embodiments, the first source/drain layer 232 may be formed byperforming a SEG process using a silicon source gas, e.g., disilane(Si₂H₆) gas and a carbon source gas, e.g., monomethylsilane (SiH₃CH₃)gas to form a single crystalline silicon carbide layer. Alternatively,the SEG process may be performed using only the silicon source gas,e.g., disilane (Si₂H₆) gas to form a single crystalline silicon layer.In some embodiments, an n-type impurity source gas, e.g., phosphine(PH₃) gas may be also used to form a single crystalline silicon carbidelayer doped with n-type impurities or a single crystalline silicon layerdoped with n-type impurities. Thus, the first source/drain layer 232 mayserve as a source/drain region of an NMOS transistor.

In some embodiments, the second source/drain layer 234 may be formed byperforming a SEG process using a silicon source gas, e.g.,dichlorosilane (SiH₂Cl₂) gas, a germanium source gas, e.g., germane(GeH₄) gas to form a single crystalline silicon-germanium layer. In someembodiments, a p-type impurity source gas, e.g., diborane (B₂H₆) gas maybe also used to form a single crystalline silicon-germanium layer dopedwith p-type impurities. Thus, the second source/drain layer 234 mayserve as a source/drain region of a PMOS transistor.

Each of the first and second source/drain layers 232 and 234 may fillthe third recess 220, and may be further grown to contact a portion ofthe gate spacer 160. However, the third recess 220 may have the shapelimited by the second sacrificial pattern 184 remaining on the secondisolation pattern 125, and thus each of the first and secondsource/drain layers 232 and 234 filling the third recess 220 may alsohave a shape limited by the second sacrificial pattern 184. That is,each of sidewalls of a cross-section of each of the source/drain layers232 and 234 taken along the second direction may include a curvedportion having a slope decreasing (e.g., gradually) from a bottom towarda top thereof.

Thus, each of the first and second source/drain layers 232 and 234 maybe formed to have the cross-sectional shape illustrated with referenceto FIGS. 1 to 4.

Referring to FIGS. 31 to 33, after removing the remaining secondsacrificial pattern 184, a first insulating interlayer 240 may be formedon the active fin 104 and the isolation patterns 120 and 125 to coverthe dummy gate structure, the gate spacer 160, and the first and secondsource/drain layers 232 and 234 with a sufficient thickness and then maybe planarized until an upper surface of the dummy gate electrode 140 ofthe dummy gate structure may be exposed. In the planarization process,the gate mask 150 may be also removed, and an upper portion of the gatespacer 160 may be partially removed.

The first insulating interlayer 240 may be formed of an oxide, e.g.,silicon oxide. The planarization process may be performed by a CMPprocess and/or an etch back process.

Referring to FIG. 34, after removing the remaining second sacrificialpattern 184, an additional SEG process may be performed to form thirdand fourth source/drain layers 233 and 235 having the cross-sectionalshape shown in FIG. 5. The additional SEG process may not be performed,and hereinafter, only the case without the additional SEG process willbe illustrated.

Referring to FIGS. 35 to 37, the exposed dummy gate electrode 140 andthe dummy gate insulation pattern 130 under the dummy gate electrode 140may be removed to form an opening 250 exposing an inner sidewall of thegate spacer 160 and an upper surface of the active fin 105, i.e., anupper surface of the upper active pattern 105 a.

In some embodiments, the exposed dummy gate electrode 140 may be removedby a dry etch process first, and then by a wet etch process usingammonia hydroxide (NH₄OH) as an etching solution. The dummy gateinsulation pattern 130 may be removed by a dry etch process and/or a wetetch process using hydrogen fluoride (HF) as an etching solution.

Referring to FIGS. 38 to 40, a gate structure 290 may be formed to fillthe opening 290.

After performing a thermal oxidation process on the upper surface of theactive fin 105 exposed by the opening 250 to form an interface pattern260, a gate insulation layer may be formed on the interface pattern 260,the isolation patterns 120 and 125, the gate spacer 160, and the firstinsulating interlayer 240, and a gate electrode layer may be formed onthe gate insulation layer to sufficiently fill a remaining portion ofthe opening 250.

In some embodiments, the gate insulation layer may be formed to includea metal oxide having a dielectric constant higher than silicon oxide,e.g., hafnium oxide, tantalum oxide, zirconium oxide, or the like, by aCVD process or an ALD process. The gate electrode layer may be formed toinclude a material having a low resistance, e.g., a metal such asaluminum, copper, tantalum, etc., or a metal nitride thereof by an ALDprocess, a physical vapor deposition (PVD) process, or the like. In someexample embodiments, a heat treatment process, e.g., a rapid thermalannealing (RTA) process, a spike rapid thermal annealing (spike RTA)process, a flash rapid thermal annealing (flash RTA) process or a laserannealing process may be further performed. In some embodiments, thegate electrode layer may be formed of doped polysilicon.

In some embodiments, the interface pattern 260 may be formed by a CVDprocess, an ALD process, or the like, similarly to the gate insulationlayer or the gate electrode layer. In this case, the interface pattern260 may be formed not only on an upper surface of the active fin 105 butalso on upper surfaces of the isolation patterns 120 and 125 and aninner sidewall of the gate spacer 160.

The gate electrode layer and the gate insulation layer may be planarizeduntil an upper surface of the first insulating interlayer 240 may beexposed to form a gate insulation pattern 270 on the interface pattern260 and the inner sidewall of the gate spacer 160, and a gate electrode280 filling the remaining portion of the opening 250 on the gateinsulation pattern 270. Accordingly, a lower surface and a sidewall ofthe gate electrode 280 may be covered by the gate insulation pattern270. In some embodiments, the planarization process may be performed bya CMP process and/or an etch back process.

The interface pattern 260, the gate insulation pattern 270 and the gateelectrode 280 sequentially stacked may form the gate structure 290, andthe gate structure 290 together with the first and second source/drainlayers 232 and 234 may form a PMOS transistor or an NMOS transistoraccording to the conductivity type of the impurities doped into thefirst and second source/drain layers 232 and 234.

Referring to FIGS. 41 to 43, a second insulating interlayer 300 may beformed on the first insulating interlayer 240, the gate structure 290,and the gate spacer 160, and first and second holes 310 and 315 may beformed through the first and second insulating interlayers 240 and 300to expose upper surfaces of the first and second source/drain layers 232and 234, respectively.

The second insulating interlayer 300 may be formed of a materialsubstantially the same as or different from that of the first insulatinginterlayer 240. For example, the second insulating interlayer 300 may beformed of an oxide, e.g., silicon oxide.

The first and second holes 310 and 315 may be formed by forming aphotoresist pattern (not shown) on the second insulating interlayer 300,and performing a dry etch process using the photoresist pattern as anetching mask. In some embodiments, the first and second holes 310 and315 may be formed to be self-aligned with the gate spacer 160.

Referring to FIGS. 1 to 4 again, first and second metal silicidepatterns 320 and 325 may be formed on the first and second source/drainlayers 232 and 234 exposed by the first and second holes 310 and 315,respectively.

In some embodiments, after forming a metal layer on the exposed firstand second source/drain layers 232 and 234 and the second insulatinginterlayer 300, a heat treatment may be performed on the metal layer,and an unreacted portion of the metal layer may be removed to form thefirst and second metal silicide patterns 320 and 325 on the first andsecond source/drain layers 232 and 234, respectively. The metal layermay be formed of, e.g., cobalt, nickel, etc.

In some embodiments, the first and second metal silicide patterns 320and 325 may be formed on the first and second source/drain layers 232and 234, respectively, to be separated therefrom. In some embodiments,no metal silicide pattern may be formed on the first and secondsource/drain layers 232 and 234.

First and second contact plugs 330 and 335 may be formed to fill thefirst and second holes 310 and 315. The first and second contact plugs330 and 335 may be formed by forming a conductive layer on uppersurfaces of the first and second metal silicide patterns 320 and 325 orthe first and second source/drain layers 232 and 234, sidewalls of thefirst and second holes 310 and 315, and an upper surface of the secondinsulating interlayer 300 to sufficiently fill the first and secondholes 310 and 315, and planarizing the conductive layer until the uppersurface of the second insulating interlayer 300 may be exposed. In someembodiments, the conductive layer may be formed of a metal, a metalnitride, doped polysilicon, etc. In some embodiments, each of the firstand second contact plugs 330 and 335 may be formed to include a barrierlayer (not shown) covering a bottom and a sidewall of the conductivelayer. The barrier layer may be formed to include a metal nitride layerand/or a metal.

By the above processes, the semiconductor device may be manufactured.

FIGS. 44 and 45 are cross-sectional views illustrating a semiconductordevice in accordance with example embodiments. FIG. 44 is across-sectional view taken along the line A-A′ of FIG. 1, and FIG. 45 isa cross-sectional view taken along the line C-C′ of FIG. 1.

This semiconductor device may be substantially the same as or similar tothat of FIGS. 1 to 4, except for the shapes of the active fin and thesource/drain layers. Thus, like reference numerals refer to likeelements, and detailed descriptions thereon are omitted herein.

Referring to FIGS. 44 and 45, the semiconductor device may include theactive fin 105, the gate structure 290, and the first and secondsource/drain layers 232 and 234 on the substrate 100. The semiconductordevice may further include the gate spacer 160, the first and secondcontact plugs 330 and 335, the first and second metal silicide patterns320 and 325, and the first and second insulating interlayers 240 and300.

The active fin 105 may include lower and upper active patterns 105 b and105 a sequentially stacked and integrally formed with each other. Insome embodiments, the active fin 105 may have a unitary structureincluding the lower and upper active patterns 105 b and 105 a. Theactive fins 105 formed in the first and second regions I and II may bereferred to as first and second active fins, respectively.

Each of the source/drain layers 232 and 234 may be formed at least oneof the active fins 105 disposed in the second direction adjacent thegate structure 290 extending in the second direction. Referring to FIG.45, each of the source/drain layers 232 and 234 may fill a recess (notshown) that may be formed at an upper portion of the upper activepattern 105, and an upper portion of each of the source/drain layers 232and 234 may contact an outer sidewall of the gate spacer 160. Referringto FIG. 44, each of the source/drain layers 232 and 234 may contactupper surfaces of the upper active patterns 105 a, and may protrudeupwardly.

The cross-section of the first source/drain layer 232 taken along thesecond direction may include an upper surface, a lower surface and asidewall, and the shapes of the upper surface and the sidewall thereofmay be substantially the same as or similar to those of thecross-section of the first source/drain layer 232 shown in FIGS. 1 to 4.

However, the lower surface of the cross-section may further include aconcave portion corresponding to the protruding upper active pattern 105a. That is, the cross-section may include two protrusion portions 16 aand 16 b instead of the two fifth linear portions 15 a and 15 b.

FIGS. 46 to 51 are plan views and cross-sectional views illustrating amethod of manufacturing a semiconductor device in accordance withexample embodiments. FIGS. 46 and 49 are plan views, FIGS. 47 and 50 arecross-sectional views taken along the lines A-A′ of corresponding planviews, respectively, FIG. 44 is a cross-sectional view taken along theline B-B′ of a corresponding plan view, and FIGS. 48 and 51 arecross-sectional views taken along the lines C-C′ of corresponding planviews, respectively.

This method may include processes substantially the same as or similarto those illustrated with reference to FIGS. 6 to 43, and detaileddescriptions thereon are omitted herein.

First, processes substantially the same as or similar to thoseillustrated with reference to FIGS. 6 to 19 may be performed.

Referring to FIGS. 46 to 48, processes substantially the same as orsimilar to those illustrated with reference to FIGS. 20 to 22 may beperformed. However, an upper portion of the exposed active fin 105 maybe removed to form a fourth recess 205, which may be formed in the upperactive pattern 105 a and may not expose an upper surface of the loweractive pattern 105 b.

Referring to FIGS. 49 to 51, processes substantially the same as orsimilar to those illustrated with reference to FIGS. 23 to 30 may beperformed.

Thus, the fourth recess 205 may expand to a fifth recess (not shown),and first and second source/drain layers 232 and 234 partially fillingthe fifth recess may be formed on the first and second active fins,respectively.

In some embodiments, the first and second source/drain layers 232 and234 may be formed by a SEG process using an upper surface of the upperactive fin 105 a exposed by the fifth recess as a seed layer. The firstand second source/drain layers 232 and 234 may be formed to have shapessubstantially the same as those of the first and second source/drainlayers 232 and 234 shown in FIGS. 29 and 30, except for lower surfacescorresponding to the upper active fin 105 a.

Then, processes substantially the same as or similar to thoseillustrated with reference to FIGS. 31 to 43, and FIGS. 1 to 4 may beperformed to complete the semiconductor device.

FIGS. 52 and 54 are a plan view and cross-sectional views illustrating asemiconductor device in accordance with example embodiments. FIG. 52 isa plan view, FIG. 53 is a cross-sectional view taken along the line A-A′of FIG. 52, and FIG. 54 is a cross-sectional view taken along the lineC-C′ of FIG. 52.

This semiconductor device may be substantially the same as or similar tothat of FIGS. 1 to 4, except for the shapes of the source/drain layersand the contact plugs. Thus, like reference numerals refer to likeelements, and detailed descriptions thereon are omitted herein.

Referring to FIGS. 52 to 54, the semiconductor device may include theactive fin 105, the gate structure 290, and the first and secondsource/drain layers 232 and 234 on the substrate 100. The semiconductordevice may further include the gate spacer 160, the first and secondcontact plugs 330 and 335, the first and second metal silicide patterns320 and 325, and the first and second insulating interlayers 240 and300.

Referring to FIG. 54, each of the first and second source/drain layers232 and 234 may fill a recess (not shown), which may be formed in theupper active fin 105 a and expose an upper surface of the lower activefin 105 b. An upper surface of each of the first and second source/drainlayers 232 and 234 may be higher than a lower surface of the gate spacer160 and lower than an upper surface thereof. The first and secondsource/drain layers 232 and 234 shown in FIGS. 1 to 4 may contact theouter sidewall of the gate spacer 160, while the first and secondsource/drain layers 232 and 234 shown in FIG. 54 may not contact theouter sidewall of the gate spacer 160. Thus, the first and secondcontact plugs 330 and 335 self-aligned with the gate spacer 160 may beformed between upper sidewalls of the first and second source/drainlayers 232 and 234 and the outer sidewall of the gate spacer 160.

The first and second metal silicide patterns 320 and 325 may be formedat upper portions of the first and second source/drain layers 232 and234, respectively, or on upper surfaces of the first and secondsource/drain layers 232 and 234, respectively, to be separatedtherefrom.

FIGS. 55 to 63 are plan views and cross-sectional views illustrating amethod of manufacturing a semiconductor device in accordance withexample embodiments. Particularly, FIGS. 55, 59 and 62 are plan views,FIGS. 56 and 60 are cross-sectional views taken along the lines A-A′ ofcorresponding plan views, respectively, and FIGS. 57, 58, 61 and 63 arecross-sectional views taken along the lines C-C′ of corresponding planviews, respectively.

This method may include processes substantially the same as or similarto those illustrated with reference to FIGS. 6 to 43, and detaileddescriptions thereon are omitted herein.

First, processes substantially the same as or similar to thoseillustrated with reference to FIGS. 6 to 16 may be performed.

Referring to FIGS. 55 to 57, processes substantially the same as orsimilar to those illustrated with reference to FIGS. 17 to 19 may beperformed.

However, no CMP process may be performed on the sacrificial layer 180,and only the etch back process may be performed. Thus, the sacrificiallayer 180 may be etched until an upper surface of the active fin 105 maybe exposed so that a portion of the sacrificial layer 180 on the uppersurface of the dummy gate structure having a relatively thick thickness,and a portion of the sacrificial layer 180 on the gate spacer 160 mayremain, which may be referred to as a third sacrificial pattern 186.

Referring to FIG. 58, processes substantially the same as or similar tothose illustrated with reference to FIGS. 20 to 22 may be performed.

Thus, an upper portion of the active fin 105 not covered by the dummygate structure, the gate spacer 160 and the third sacrificial pattern186 may be removed to form a first recess 200.

In some embodiments, the upper active pattern 105 a of the active fin105 may be removed to form the first recess 200, and thus an uppersurface of the lower active pattern 105 b may be exposed.

Referring to FIGS. 59 to 61, processes substantially the same as orsimilar to those illustrated with reference to FIGS. 28 to 30.

Thus, a SEG process may be performed to form first and secondsource/drain layers 232 and 234, which may be grown to contact asidewall of the third sacrificial pattern 186.

Referring to FIGS. 62 and 63, processes substantially the same as orsimilar to those illustrated with reference to FIGS. 31 to 33 may beperformed.

However, the third sacrificial pattern 186 together with the secondsacrificial pattern 184 may be removed, and thus the first and secondinsulating interlayer 240 may be formed between the gate spacer 160 andthe source/drain layers 232 and 234.

Processes substantially the same as or similar to those illustrated withreference to FIGS. 34 to 43 and FIGS. 1 to 4 may be performed tocomplete the semiconductor device.

However, the first and second contact plugs 330 and 335 on uppersurfaces of the first and second source/drain layers 232 and 234 or thefirst and second metal silicide patterns 320 and 325, which may beself-aligned with the gate spacer 160, may be also formed between theouter sidewall of the gate spacer 160 and the first and secondsource/drain layers 232 and 234.

The above semiconductor device and the method of manufacturing the samemay be applied to various types of memory devices including a finFET andsource/drain layers formed by a SEG process. For example, thesemiconductor device and the method of manufacturing the same may beapplied to logic devices such as central processing units (CPUs), mainprocessing units (MPUs), or application processors (APs), or the like.Additionally, the semiconductor device and the method of manufacturingthe same may be applied to volatile memory devices such as DRAM devicesor SRAM devices, or non-volatile memory devices such as flash memorydevices, PRAM devices, MRAM devices, RRAM devices, or the like.

The foregoing is illustrative of example embodiments and is not to beconstrued as limiting thereof. Although a few example embodiments havebeen described, those skilled in the art will readily appreciate thatmany modifications are possible in the example embodiments withoutmaterially departing from the novel teachings and advantages of thepresent inventive concepts. Accordingly, all such modifications areintended to be included within the scope of the present inventiveconcepts as defined in the claims. Therefore, it is to be understoodthat the foregoing is illustrative of various example embodiments and isnot to be construed as limited to the specific example embodimentsdisclosed, and that modifications to the disclosed example embodiments,as well as other example embodiments, are intended to be included withinthe scope of the appended claims.

What is claimed is:
 1. A semiconductor device, comprising: a pluralityof active fins each extending in a first direction on a substrate; agate structure on the plurality of active fins, the gate structureextending in a second direction that is different from the firstdirection; and a first source/drain layer on the plurality of activefins and adjacent a side of the gate structure, wherein at least one ofopposing sidewalls of a cross-section of the first source/drain layerthat is taken along the second direction includes a first curved portionhaving a slope with respect to an upper surface of the substrate, and anabsolute value of the slope of the first curved portion decreases from abottom of the first curved portion that is close to the substrate to atop thereof, and wherein the cross-section of the first source/drainlayer includes an upper surface including first and second linearportions having first and second slopes, respectively, with respect tothe upper surface of the substrate, and the opposing sidewalls of thecross-section of the first source/drain layer are between the uppersurface of the cross-section of the first source/drain layer and thesubstrate.
 2. The semiconductor device of claim 1, wherein thecross-section of the first source/drain layer further includes a lowersurface including third and fourth linear portions having the first andsecond slopes, respectively, with respect to the upper surface of thesubstrate, and wherein each of the opposing sidewalls of thecross-section of the first source/drain layer connects the upper surfaceand the lower surface.
 3. The semiconductor device of claim 2, whereinthe lower surface of the cross-section of the first source/drain layerfurther includes a fifth linear portion connecting one of the thirdlinear portions to one of the fourth linear portions and having a zerodegree slope with respect to the upper surface of the substrate.
 4. Thesemiconductor device of claim 1, wherein the plurality of active finsinclude two first active fins, wherein the first linear portioncomprises two first linear portions each having the first slop withrespect to the upper surface of the substrate, and the second linearportion comprises two second linear portions each having the secondslope with respect to the upper surface of the substrate, and whereinthe cross-section of the first source/drain lay further includes a lowersurface including two third linear portions each having the first slopewith respect to the upper surface of the substrate, two fourth linearportions each having the second slope with, respect to the upper surfaceof the substrate, and two fifth linear portions each connecting one ofthe two third linear portions to one of the two fourth linear portions,wherein a first sidewall of the opposing sidewalls of the cross-sectionof the first source/drain layer connects one of the two first linearportions of the upper surface and one of the two fourth linear portionsof the lower surface, and a second sidewall of the opposing sidewalls ofthe cross-section of the first source/drain layer connects one of thetwo second linear portions of the upper surface and one of the two thirdlinear portions of the lower surface.
 5. The semiconductor device ofclaim 1, wherein the opposing sidewalls of the cross-section of thefirst source/drain layer are symmetrical with respect to an imaginaryline passing a center of the first source/drain layer and extending in avertical direction that is substantially perpendicular to the uppersurface of the substrate.
 6. The semiconductor device of claim 1,wherein the plurality of active fins include a plurality of first activefins in a first region of the substrate and a plurality of second activefins in a second region of the substrate, and the second region isspaced apart from the first region in the second direction, wherein thesemiconductor device further comprises a second source/drain layer, atleast one of opposing sidewalls of a cross-section of the secondsource/drain layer that is taken along the second direction includes asecond curved portion having a slope with respect to the upper surfaceof the substrate, and an absolute value of the slope of the secondcurved portion decreases from a bottom of the second curved portion thatis close to the substrate to a top thereof, and wherein the first andsecond source/drain layers are spaced apart from each other in thesecond direction.
 7. The semiconductor device of claim 6, wherein adistance between ones of the plurality of first active fins and adistance between ones of the plurality of second active fins are lessthan a distance between the plurality of first active fins and theplurality of second active fins.
 8. The semiconductor device of claim 1,wherein the first source/drain layer includes silicon-germanium, siliconand/or silicon carbide.
 9. The semiconductor device of claim 1, whereinthe gate structure includes an interface pattern, a gate insulationpattern and a gate electrode sequentially stacked on the plurality ofactive fins.
 10. The semiconductor device of claim 9, wherein theinterface pattern, the gate insulation pattern and the gate electrodeinclude silicon oxide, a metal oxide having a dielectric constant higherthan silicon oxide, and a metal, respectively.
 11. The semiconductordevice of claim 1, further comprising gate spacers on respectiveopposing sidewalls of the gate structure that are spaced apart from eachother in the first direction, wherein the first source/drain layercontacts an outer sidewall of one of the gate spacers.
 12. Thesemiconductor device of claim 1, wherein the first source/drain layerdirectly contacts the plurality of active fins.
 13. A semiconductordevice, comprising: an active fin on a substrate; a gate structure onthe active fin; and a source/drain layer on the active fin and adjacenta side of the gate structure, wherein, at least one of opposingsidewalls of a cross-section of the source/drain layer includes a curvedportion having a slope with respect to an upper surface of thesubstrate, and an absolute value of the slope of the curved portiondecreases from a bottom of the curved portion that is close to thesubstrate to a top thereof, wherein the substrate includes first andsecond regions, wherein the active fin includes a plurality of firstactive fins in the first region and a plurality of second active fins inthe second region, wherein the source/drain layer includes a firstsource/drain layer on the plurality of first active fins and a secondsource/drain layer on the plurality of second active fins, wherein eachof the plurality of first active fins and the plurality of second activefins extends in a first direction, and the plurality of first activefins and the plurality of second active fins are arranged in a seconddirection that is different from the first direction, wherein the firstand second regions are spaced apart from each other in the seconddirection, wherein the cross-section of the source/drain layer is takenalong the second direction, wherein a distance between ones of theplurality of first active fins and a distance between ones of theplurality of second active fins are less than a distance between theplurality of first active fins and the plurality of second active fins,and wherein the first and second source/drain layers are spaced apartfrom each other in the second direction.
 14. A semiconductor device,comprising: a plurality of active fins each extending longitudinally ina first horizontal direction on a substrate, wherein the firsthorizontal direction is parallel to an upper surface of the substrate; agate structure on the plurality of active fins, the gate structureextending in a second horizontal direction that is different from thefirst horizontal direction and parallel to the upper surface of thesubstrate; first and second gate spacers on respective sidewalls of thegate structure opposed to each other in the first horizontal direction;and a first source/drain layer on the plurality of active fins andadjacent the first gate spacer, wherein an upper surface of the firstsource/drain layer is higher than lower surfaces of the first and secondgate spacers, wherein the first source/drain layer is spaced apart fromthe first gate spacer in the first horizontal direction, wherein atleast one of opposing sidewalls of a cross-section of the firstsource/drain layer that is taken along the second horizontal directionincludes a first curved portion having a slope with respect to the uppersurface of the substrate, and an absolute value of the slope of thefirst curved portion decreases from a bottom of the first curved portionthat is close to the substrate to a top thereof, wherein the pluralityof active fins includes a plurality of first active fins in a firstregion of the substrate and a plurality of second active fins in asecond region of the substrate, and the first source/drain layer is onthe plurality of first active fins, wherein the semiconductor devicefurther comprises a second source/drain layer on the plurality of secondactive fins at least one of opposing sidewalls of a cross-section of thesecond source/drain layer that is taken along the second horizontaldirection includes a second curved portion having a slope with respectto the upper surface of the substrate, and an absolute value of theslope of the second curved portion decreases from a bottom of the secondcurved portion that is close to the substrate to a top thereof, andwherein the first source/drain layer includes an epitaxial layerincluding silicon and/or silicon carbide, and the second source/drainlayer includes an epitaxial layer including silicon-germanium.
 15. Thesemiconductor device of claim 14, further comprising a contact plugelectrically connected to the first source/drain layer, wherein thecontact plug is disposed in a space between the first gate spacer andthe first source/drain layer.
 16. The semiconductor device of claim 14,wherein the first and second regions are spaced apart from each other inthe second horizontal direction, and wherein the first and secondsource/drain layers are spaced apart from each other in the secondhorizontal direction.
 17. The semiconductor device of claim 14, whereinan entirety of the first source/drain layer is spaced apart from thefirst gate spacer.
 18. The semiconductor device of claim 14, wherein thefirst source/drain layer directly contacts the plurality of first activefins.